Coal is commonly analyzed by its major components, which are moisture, volatile gases, fixed carbon, ash, and sulfur. Volatile gases and fixed carbon are the fuel elements. Water, ash and sulfur are the impurities. The higher rank (harder) coals are commonly classified according to their fixed carbon content, and the lower (softer) coals according to their heat value. Arkansas Valley coals are all of high rank. They range from low-volatile bituminous coal in the western part of the Arkansas to semianthracite in the eastern part.

Table 1 summarizes analyses of 258 samples of Arkansas coal and shows the average analyses of coal that has been mined from various coal beds and fields in the state. Heat value is shown in British thermal units (Btu). One of the principal advantages of Arkansas coal is that it gives off little smoke when burned. Another is that its sulfur content is relatively low, compared to many coals mined in the United Stats and elsewhere.